None.
This invention relates to lumber stacking equipment and more particular to lumber stacking equipment having mechanisms for placing stickers between board layers during the formation of a stack.
Lumber boards are freshly cut from logs and then generally sorted by width and length. Frequently the boards are then arranged in a stack for drying in a dry atmosphere such as a dry kiln. During the stacking process, elongated wooden slats called xe2x80x9cstickersxe2x80x9d are placed transversely between layers or courses of boards at spaced intervals along the length of the stack to separate the layers. Usually, the stickers have lengths equal to the width of the stack and are positioned transverse to the boards in the stack. The stickers are placed at desired intervals along the length of the stack to separate the layers of boards to enable drying gases to circulate through the stack to uniformly dry the boards. Dry boards are less likely to warp or subsequently change shape thereby increasing their value.
Originally xe2x80x9cstickeringxe2x80x9d was performed manually while the stack was being formed by placing the stickers by hand at the desired Intervals on top of each layer after the layer was placed on the stack, prior to placing the succeeding layer. Later on, the stickers were manually placed in spaced stickers magazines along side or over the stack and fed in unison and placed on the then top layer of the stack prior to a succeeding layer being placed in the stack.
Mr. Sidney L. Lunden thereafter invented a very commercially successful xe2x80x9cSticker Placement Device For Lumber Stacking Apparatusxe2x80x9d in which the stickers are feed from a common source to sticker stations on the stacking machine. The stickers are then lifted up and placed underneath the succeeding layer as the succeeding layer was being removed from the stacker and placed on the stack. Such a combination stickering and stacking machine revolutionized the process, thereby dramatically increasing the efficiency of the process and reducing the number of operators required to operate the machine. The combined apparatus is the subject of U.S. Pat. No. 3,904,044 granted on Sep. 9, 1975. As a testament to its design, many of the machines incorporating the original invention are still in commercial operation.
Since the time of his original invention, Mr. Lunden has made several significant improvements which are the subject of several patents, including U.S. Pat. No. 4,253,787 granted Mar. 3, 1981; U.S. Pat. No. 4,324,521 granted Apr. 13, 1982; and U.S. Pat. No. 5,993,145 granted Nov. 30, 1999.
The present application is a further significant improvement which enables the stacking apparatus to operate at high speeds of up to stacking ten layers a minute while reducing the chances of a sticker malfunction or xe2x80x9csticker jamxe2x80x9d and thereby reducing the occasions in which the apparatus must be stopped to clear a problem.